Nearly half of the British women might be lacking an important source of vitamin A due to previously undetected genetic defect.
The vitamin helps the immune system ward off common infections such as flu and is important for healthy skin.
Although dairy products and eggs are known as a rich source of vitamin A, another key source is beta-carotene, the orange pigment in carrots, which is converted into the vitamin by the body.
However, University of Newcastle team has identified a genetic variation that blocks the ability beta-carotene to produce vitamin A.
"Vitamin A is very important, particularly now when we are all trying to fight off winter colds and flu. It reduces the risk of inflammation such as that with chest infections," the Daily Express quoted Dr Georg Lietz, head of the University of Newcastle team as saying.
The researchers are conducting further studies to establish if the problem applies to men.